An aerial view shows Burj Dubai, the world's tallest tower, in Dubai. The city has succeeded in attracting wealthy Persian Gulf elites.

Marwan NaamaniAFP/Getty Images

This week, we're asking what it really means to live in a world with 7 billion people. For some answers, we visit Karachi, Pakistan.

The grandest expression of the world's population growth is in the word "megacity." Dozens of these cities of more than 10 million now ring the globe, like a string of oversized pearls. In a megacity, people and ideas clash: The ancient collides with the modern; secular with religious; global with local. In Karachi, Pakistan, those forces can be seen in the story of a single piece of real estate.

Vying To Take The Global Stage

Karachi's population has grown to more than 13 million. On a recent visit, a trip down a tree-lined avenue showed how times have changed for the city, from when it last attempted to assert itself on the global level.

Our guide is "Tony" Tufail Shaikh, an entertainer, entrepreneur and onetime waterfront developer in Karachi. He's driving through an upscale district of consulates, hotels and historic mansions from British colonial times.

It's also a district with a security problem. Gunmen stand at many gates to protect the occupants, prompting the question of whether there were always so many guards in the city.

"No way," Shaikh says. "One time, the city was full of life. People could walk on the street at 4 o'clock in the morning; the gates were open, there were no guards."

This city has changed since the 1970s, when it seemed to have a brighter future.

We can trace that change by learning the story of a single piece of beachfront property that Shaikh once owned. His vision was to attract global elites by turning Karachi into an entertainment capital in the late '70s.

It would have been anchored by a 100,000 square-foot casino.

"When I built this casino, there was no building here, on the left and right both, it was a flat land," he says, pointing out a row of buildings.

Shaikh was once a nightclub owner; he served drinks and brought in dancing girls. But he had bigger visions, of a city as lovely as Paris, and as alluring as Beirut, the Lebanese capital. He wanted to attract Arab oil sheiks, who'd lately become wealthy providing the fuel for the expanding economy of an expanding world population.

Shaikh was actually able to build his casino in this Muslim country — a large building with a vast roof, curving like two wings of a bird. He had the right political backing. Pakistan's prime minister had been one of his nightclub customers, and then a friend.

"We were ready" for the casino's first day, he says. "We had printed invitation cards; I was just waiting for the date, from the prime minister, Zulfikar Ali Bhutto, to give me a date for the opening."

A Shift For Pakistan, And Karachi

Shaikh was waiting for that final approval in 1977 when a moment came that shifted many fortunes in this part of the world. He got a phone call in the middle of the night. His political sponsor had just been overthrown in a military coup.

"In those days, I had a drink and then I was just thinking, what now," he says. "Then again, I thought, 'You'll have to start all over again.'"

The new military ruler was a religious conservative. And in an era of rising fundamentalism, Shaikh's casino was never allowed to open; Karachi didn't become the playground of Persian Gulf elites in the 1970s. In the years that followed, that role slipped instead to the glittering, swiftly growing city of Dubai.

Dubai managed to mix global and local ideas, secular and religious concerns, in a way that Shaikh's Karachi did not.

Now, 30 years later, he is asked if he's gotten over the disappointment.

"No, I'm not," he says. "I still feel sorry for people, for the future generation – you know, where are they heading?"

As it happens, many people in Pakistan's new generation are heading to Karachi, where the population has soared.

It's part of a swiftly growing nation, now one of the most populous in the world. And if you want a cautionary tale about living in a world with more than 7 billion people, Pakistan could be it.

The population has outgrown the infrastructure. People face constant shortages of electricity, and worry about the water supply. Religious conflicts, terrorism and political chaos make it hard to focus on those basic problems, which grow along with the population.

Where A Casino Stood, A Mall Rises

Still, at Shaikh's old waterfront property, people are making another bid to claim a share of the global economy.

Years ago, his stillborn casino was torn down. Now, men are working on metal-pipe scaffolding inside a vast new structure. The new owner, like the old one, wants to attract the wealthy.

Workmen are building office towers, and cutting stone tiles for a shopping mall — 1 million square feet of Western chain stores and upscale restaurants.

"We expect many foreigners and multinational chief executives," says Jabir Hussain Dada, the sales manager. "They'll be dining over here in the Landstimer, obviously. It will be full in the evenings, because they're going to come along with their families."

Dada walked through the construction zone, showing off the mall's planned features.

"This is the area for the banquet hall – easily, 1,500 people can be accommodated," he says, pointing at an area that includes a view of the Arabian Sea.

The mall and office complex are modeled after Dubai — that center of wealth and entertainment that Karachi has already missed one chance to be. The owner of this project travels often to Dubai for inspiration.

One of his new office towers is shaped like a sail, somewhat like one of Dubai's landmark buildings. But there remains the problem that Karachi is not Dubai — but rather, a city in a vast and growing country, increasingly at war with itself.

Asked about the timing of the project, Dada says, "We are very hopeful that it's going to be a turnaround in a year or so, so what we are doing, [is] that we are developing very rapidly all the structure, so when the good time comes, everything will be operational."

So the workmen keep on cutting stone tiles, pausing every now and again to kneel on mats on the concrete floor and pray.

Dada leads the way into an office-tower elevator. Of course, the elevators must run on electricity — even in a city, and a nation, that has outgrown its power supply. Karachi suffers hours of blackouts every single day.

The government has given the developers assurances that the complex will have the power it needs. But there are no guarantees.

"Actually, we do not rely on" the government alone, Dada says. "It's like, something we have realized that we have to do it ourselves. Whatever government is giving us, we are happy with it."

And for what the governments doesn't provide, the project will have to include generators. It may only get harder to obtain basic services as Pakistan's population grows even more, over the next 40 years.

In a world with 7 billion people and growing, some people, some cities and some nations will surely come out winners. Others may be scrambling just to keep the lights on.

Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.